US stock futures mixed as Apple falls on margin warning, midterm results awaited

U.S. stock index futures reflect a mixed response as crude oil prices trend upwards ahead of midterm election outcomes. Apple's shares took a hit following its announcement regarding rising costs and potential holiday-quarter margin impacts. Despite Palantir Technologies exceeding revenue estimates, its stock plummeted post-results. Analysts are warning of heightened market volatility depending on elections and government expenditure.